Periodontal disease is a chronic bacterial condition associated with receding gums and tooth loss in adults. Outside of regular brushing and flossing, effective measures to allay this disease are limited, Shimazaki, of Kyushu University in Fukuoka, Japan, and colleagues note in the Journal of Periodontology.

Previous research identified a lower occurrence of periodontal disease among people who eat high amounts of dairy products, but did not identify which dairy products were most beneficial, the researchers report.

Shimazaki's team assessed the severity of periodontal disease in 942 men and women, aged 40 to 79 years, and their intake of milk, cheese, and lactic acid foods.

They found that people with generalized (more advanced) periodontal disease had a lower intake of lactic acid foods than people with localized (less advanced) periodontal disease.

Compared with individuals reporting no lactic acid food intake, those eating 55 grams or more of yogurt or lactic acid drinks a day had significantly fewer markers of severe periodontal disease, the investigators note, once they made allowances for factors such as age, gender, smoking, alcohol intake, frequency of tooth brushing, blood sugar and cholesterol levels.

"The beneficial effect on periodontal disease might be based on the probiotic effect of lactobacilli found in lactic acid foods," Shimazaki told Reuters Health. Probiotics are living microorganisms, such as the Lactobacillus bacteria in yogurt that are beneficial to one's health.

The investigators suggest follow up studies that further analyze the probiotic effect of lactic acid foods by assessing the distribution of lactic acid bacteria in subjects' mouths based on the lactic acid foods they eat. Future research should also examine whether continuing intake of lactic acid foods alters the progression of periodontal disease.